Ball-mill shell and plate



w. s. MCKEE.

BALL MILL SHELL AND PLATE.

n APPLICATION FILED AUGJ 1919. 1,372,972.

Patented Mar. 29, 1921.

gli! UNITED STATES PATENT OFFICE.

WALTER S. MCKEE, OF CHICAGO, ILLINOIS, ASiSIGNOR TO AMERICAN MANGANESE i STEEL COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF MAINE.

IBALL-MILL SHELL AND PLATE.

Specification of` Letters Patent. Patented' Mar'. 299 19215;

Application filed August 1, 1919. Serial No. 314,674.,

To all whom it may concern.'

` Be it known that I, WALTER S. MGKEE, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Ball-Mill Shells and Plates, of which the following is a specification. O

This invention relates to ball mills, and particularly to a cast metal shell for such mills and to comminuter or lining plates therefor.

An object of the,present invention is to form a ball mill shell as a casting of iron, steel or alloy metal, so shaped ncross-section as to form in contour a line not unlike saw teethto conform substantially to the curvature of the lining plates forthe purpose of accommodating the uneven surfaces which for various reasons are sometimes desirable on the bottoms of liner plates.

Janother object is to form a'ball mill shell of cast metal having recesses through which the bolts for attaching the liner Aplates to theshell pass and providing the liner plates With lugs to engage the recesses, the interengaging parts serving as a means to prevent bodily movement of the plates Within the shell, thus relieving the securing bolts of shearing strains set up in mills of this character, and which strains often break the bolts, thereby permitting the plates to be dislodged causing great damage to the mill and impairing the eficient operation thereof.

A further object is to provide a shell for ball mills so shaped as to conform to the under sides of the liner plates so that a liner plate may be used which will Wear uniformly, thus reducing the amount of Waste usually experienced in discarding liner plates of the class includedi in this invention; such plates become so Worn at the thin portions as to be no longer useful.

A still further Objectis to form a ball mill lshell and liner plates therefor having coperating lugs and recesses to. prevent bodily movement of the plates Within the shell by reason of engagement of the parts, thus relieving the attaching bolts from shearing strains. i

Generally speaking, I accomplish the above and other objects by forming a ball mill shell of cast metal in the form of conventionalized saw tooth shape in section and providing a plurality of faces, the rear cast metal and of various shapes in cross.

section, the purpose being when the plates are in position to form an irregular surface Within the mill so that as same is rotated the balls will be moved to drop on the material Within the mill, thereby pulverizing the material and also serving as a means to agitate the material being treated. lin some instances the plates are made to have but slight contact With the inside of the shell. ln such instances filler blocks are employed in order that the plate may have a continu uous backing, which backing is necessary to support the plates against breakage. rf`he plates used in the present style of mill are substantially Wedge-shaped in cross-section, the securing means passing through the thicker portion of the plate. lt has been found in practice that as these plates become Worn the thinner portions break,` thus exposing the shell to damage by the heavy balls, which are sometimes as large as five inches in diameter; consequently When the plates become Worn it is necessary to replace them with others. ln order to provide mill liners of satisfactory size and thickness in the thin portion it-has been customary lto ,Y make the liners unnecessarily heavy at certain portions. As a consequence of this when the plate has given its maximum service the Weight of the metal involved in the plate which is then discarded is much greater than need be. I have overcome the above obj ections by employing a plate which is not much thicker at the thick end than it is at the thin end, and forming the shell of the mill as a casting making the saine in a series of faces or plates to conform to the under side of the. plates, and so take some of the load imparted to the liners.

My invention Will be more easily understood by reference to the drawlngs, Where- 1n:-

Figure 1 is a cross-sectional view of a portion of a plate mill shell and liner plates embodying my invention, and

Fig. 2 is a plan view of the preferred- .cated by the reference character 5.

` except at the bosses through which the securing bolts pass. In the form shown the shell is cast in such manner as to present av series of wavelike faces not unlike modi- `fied saw teeth. The direction of rotation of the mill is indicated by the arrow in Fig. 1, the parts being arranged accordingly. Reference to the various parts will be made with respect to the directlon of rotation of the mill. The cast metal shell is formed with a plurality of faces. Every face includes a front edge 7 and a rear edge 6. The portion of the faces adjacent the meeting edges 6 and 7 being substantially arcuate, with the rear portion 6 below the front edge 7 of the neXt succeeding face, the

adjacent-edges of the faces being joined by the walls .8 which are substantially radial.

Near the front edges of every face, the 'faces are offset forming bosses 9 with corresponding depressed portions 10 in the inner'surfaces of the several faces. The bosses 9 are provided with apertures 11 through which may pass bolts 12 for securing the liner plates in position in the mill. As the bosses are apertured, the same are necessarily thicker than the balance of the faces of the shell for affording strength about the apertures 11.

The liner plates embodying my invention are made with the under side adapted to conform to and rest on the inner surfaces .of the various faces of the mill, affording complete contact and support from front to back. The thicker or front portions of the liner plates are provided with suitable apertures 13 having counter-bored portions -14 for the reception of the heads of the nuts 12, which heads are preferably enlarged and wedge-shaped in elevation, the purpose being to hold the plates securely against the shell and to properly position the same. The inner surfaces of the plates are formed with lugs 15 adapted to engage the recesses 10 formed in the bosses 9 as before described. With the plate arranged 1n position it is noted that the rear di" following edge of the plate falls short of the shoulders formed by the radial walls '8. The rear or heel edges of the plate are upturned at 16, and are in size such as to be engaged-by the overhanging rear portion of the next preceding liner plate for the purpose of holding the rear edge of the plate 1n position, Experience has shown that when plates of this sort have been in service a certain length of time stretching or elongaion thereof takes place. This is due to th incessant dropping` of the heavy balls on the plates as the mill operates. With a plate. constructed in accordance with my invention, the front or thicker portion is held securely against bodily movement with respect to the length of the shell and whatever elongation takes place in the thinner or free portion is permitted by the peculiar construction and arrangement of the plate of'my invention. By stopping the rear edge of the plate short of the shoulder 8 and not bolting the same, the plate is permitted to elongate without shearing the securing bolts 12. It is to be noted that as the parts are shown 'in the drawings there is a slight space between the bolts 12 and the inner surfaces of the apertures in the bosses. All of the plates are of the same general shape and character so that as many plates as desirable may be made from a single set of patterns, thus reducing the cost of manufacture of the plates and making possible the carrying of fewer shapes and sizes of plates in stock by the users of ball mills.

While I have described more or less precisel the details of construction of my invention` I do not wish to be understood as limiting myself thereto, as I contemplate changes in form and the proportion of parts and the substitution of equivalents as circumstances may suggest or render expedient` without departing from the spirit of my invention.

l claim:

l. A ball mill comprising a shell of cast metal of saw-tooth construction providing u series of faces.` the rear portions of the faces being offset inwardly with respect to the front portions of the adjacent fares and being integral therewith, a substantially radial wall connecting the edges of the adjacent faces, and liner plates arranged to conform to the shape of said faces and bearing against the inner surfaces thereof, said bearing being co-extensive with the width of said plates, the adjacent plates being arranged with the rear edge of the preceding plate overlying the front edge of the succeeding plate and the front edgel of the plates terminating short of the shoulders formed in the shell and means for securing said plates to the shell.

2. A ball mill construction including a mill shell and liner plates therefor, said liner plates having curved surfaces for resting on the mill shell with the leading edges of the plates provided with means for securing the same to the shell, the contact between the plates and shell being co-extensive with wthe widths of the plates and with the followlng edges unrestrained and retained iu poimperforate and provided with an upturned end adapted to underlie the toe of the adj acent plate clear of the fastening means for the adjacent plate.

5. A ball mill construction including a mill shell having recesses therein and liner plates therefor, said liner plates having heel and toe portions, the toe portion being thickened and being provided with a lug on its under side adapted to engage a recess in the mill shell, the toe portion having a bolt opening extending through the lug, and the v heel portion having an end adapted to contact the under side of the toe` of the adjacent plate for retaining the heel in position.

6. A ball mill including ashell having a plurality of depressions formed therein, and liner plates for said mill having lugs for cooperation with said depression for preventing movement oi the plates relatively to the shell.

7. A ball'mill including a shell having a plurality of depressions formed therein, liner plates for said mill having lugs for cooperation with said depressions for preventing movement of the plates relatively to the shell, and means passing through said lugs and recesses for retaining said plates in position in said shell.v

8. A b all mill I,having its shell formed With longitudinally extending corrugations forming radial steps, and liner plates having heel and toe portions adapted to lbe secured to said steps, said plates being arranged With the toe portions thereof eX- tendingover the heel portions of adjacent plates.

9. A ball mill having its shell formed with longitudinally extending corrugations forming radial steps, liner plates having heel andv toe portions adapted to be secured to said steps, said plates being arranged With the toe portions thereofl extending over the heel portions of adj aoent plates, and means passt-hrough the toe portions for retaining said plates in position in said mill.

l0. A tubernill liner plate consisting of a curved body having a thickened toe portion with an opening therein, and a lug on the under side of the plate surrounding the opening` in said toe portion,

11. tube mill liner plate consisting of a curved body having a thickened toe portion With an opening therein, a lug on the under side of the plate surrounding the opening in. said tube portion, and means passing through said opening for securing said plate in position in a mill shell.

Signed at Chicago, Illinois', this 28th day of July, 1919.

WALTER S. MGKEE. 

